The present invention relates to an intravenous catheter assembly, and more particularly, concerns a catheter assembly which is especially useful in situations where medicament is to be delivered in intermittent periods to a patient.
For patients who require periodic intermittent medication by intravenous delivery it is desirable to make one venipuncture, insert an intravenous catheter and leave it in position for periodic use. This procedure, of course, eliminates repetitive piercing of the patient's veins each time he is to receive medication. A catheter of this type whose purpose is to remain in the patient for a prolonged time period generally has to satisfy two requirements: it must prevent blood and/or body fluids from escaping out of the catheter both when being used and during the time period when the catheter is not in use; and it must also have some provision so that the medicament can be deposited through the catheter and into the patient. Various reseal plugs are used in intravenous catheter devices, and are well known for the purpose of preventing the escape of fluids from the catheter in addition to allowing penetration by a needle for delivery of the medicament of the patient. Some typical devices which include this reseal plug or a similar variant are described in U.S. Pat. Nos. 3,585,996; 3,313,299; and 3,097,646. A catheter with a reseal plug generally has the plug, such as a thin rubber diaphragm, covering the open end of the catheter hub. This type of diaphragm is self sealing so that each time the needle makes a puncture through the diaphragm and then is withdrawn after delivering the medication to the patient, the diaphragm seals again to prevent escape of blood or other fluids from the catheter. However advantageous this type of device with reseal plug may be, some problems still arise.
In particular, many catheters which are expected to remain in the patient after initial insertion for periodic use are constructed with plastic catheter tubing. An introducer needle, inside the plastic catheter tube, is used to make the venipuncture, and then the needle is withdrawn leaving the catheter tube in the vein of the patient. The plastic tubing, being generally flexible, minimizes trauma to the patient and does not include the very sharp points and edges such as a metal catheter tubing might have, thereby reducing the risk of damage if the patient should move or roll over the catheter. In this type of catheter with plastic catheter tubing, a problem arises when medication is injected into the hub of the catheter. The attendant or clinician pierces the reseal plug at the hub of the catheter generally with a sharp pointed metal needle at the end of a syringe. If the needle penetrates too far into the catheter its sharp point may, and often times does, puncture the wall of the plastic catheter tube. This, of course, may not only damage the catheter tube but may also leave a hole in the tube so that some of the medication may not be delivered to the patient. Accordingly, while it is still desirable to permit the hypodermic needle to penetrate into the hub of the catheter for delivery of the medication, a means of preventing inadvertent puncture of the catheter tube wall is also being sought. It is to this end and the solution of the problem of puncturing the catheter tube wall that the present invention is directed.